The present exemplary embodiment relates to image processing systems and more particularly to improved image data encoding and decoding. In copiers, printers, and other document processing systems, print jobs are received from a network or from a scanner, and the image is rendered such as by printing onto paper or other printable media. In the case of color images, the incoming job often includes a number of CMYK values associated with each pixel position, for instance Cyan, Magenta, and Yellow values for three different colors and a darkness value (K), where the incoming digital data values are of a certain bit resolution, such as four 8-bit data values indicating one of 256 possible values for C, M, Y, and K. When a color image is to be rendered, the image data is obtained from a frame buffer memory that stores the image data at an output device resolution, where storage of the frame buffer data at 8-bits per data value can lead to excessive frame buffer memory size requirements, particularly for high resolution printing systems. Accordingly, there is a need for encoding techniques and systems allowing compression of incoming image data to provide 4-bit encoded image data values for storage in a frame buffer and for decoding back to 8-bit data values for rendering.